Tem

JAN 30: 4

good introduction to digestion.
inverse relation between complexity of the food molecule and how far it continues to contribute to digestion as it moves through the tube.
note distinct environments of the tract and their respective "ecologies" - 7 quarts of fluids through small intestine.
genomic "division of labor" -- our genes code for 20 enzymes to break down complex carbs but our bacterial guests code for 260 enzymes for that purpose.
Microbiota (M) like a pharmacy.

Chemistry of Typical cereal crop seed --
Note that you lose the fats in the grain to stabilize it for production purposes. Fats go rancid. Also, white bread is sweet to the taste. Because it's already breaking down into sugars (simpler carbs) even in your mouth.
historical point: total carb consumption stable over 20th c US, but types of carbs changed. Whole grains and rate of sugar absorbtion (tracked by "glycemic index")

Protein Putrefication (Does this happen alot?) - compounds produced by undigested meat in large intestine interferes with butyrate production -- important for general colonic health. Thinning of bacterial density leaves openning for pathogens and physical damage.
High fat diets can lead to higher rates of bile in the large intestine, which it doesn't handle well. secondary bile acids.
Needn't be a general health argument against meat, but he acknowledges some legitimate health advantages to a vegetarian diet. Point is that cereal fermentation might be part of the process that helps us tolerate the protein putrefication and excess bile of meat and fat.

espouses what I'm calling the "consensus healthy diet" - movement away from industrial processed food.

How the world looks to a microbiologist! "Without microbes humans wouldn't exist, but if we all disappeared, few of them would notice." 10
Introduction to the Tube and digestion
Microbiota Case against the Western Diet

Sets the history of human diet in context. Agriculture already a big change, but then industrial ag / industrial foods
Adaptability of M remarkable. Makes us omnivores.
Baseline M - cant' be health Western Diet eaters. studies of groups like Hadza -- far more diverse.
19 - Evolved Symbiotic relationship between us and bacteria --

types of symbiotic relationship - parasitic, commensal (one party benefits, little or no effect on the other), mutualism.
The heart warming story of Tremblaya princeps and Moranella endobia. (21) -- why we should be happy mutualists. Delegation and division of labor might create resiliance.

The Great Stink 1858 London, Miasma theory disproved, Cholera bacterium, not isolated until near end of century. Dr. Robert Koch.
60-70's: Abaigail Salyers: early pioneer, 2008: Human Microbiome Project
Contemporary research: gnotobiotic mice. early fecal transplant studies of [Dr. Jeffrey Gordon].

The Microbiome research we are reading seems to have implications for the following course research questions:

1. What is food?
5. What are the challenges of nutrition science as a field of knowledge and what is the state of knowledge about nutrition, broadly?
6. What is a nutritious diet?
10. How should I critically assess my own food practices in light of my understanding of the nature of food and food culture?

Here are some possible theoretical claims for you to evaluate in terms of their plausibility and their own implications:

Your food doesn't just feed you.
Your food doesn't just nourish you, it also supplies a pharmacy in your gut. These effects cut across the health spectrum and life span.
You exist as a distinct organism, but you cannot survive outside of the symbiotic relationships you have with bacteria and other organisms that call you home.
Mental health is influenced by the health of our M.
We have co-evolved with our Microbiome.
The interic nervous system is an ecology.
Some of the requirements of industrial food production are at odds with the requirements of a health Microbiome.

In small group discussion, consider how information about the Microbiome might change your approach to questions like "What is Food?" Then look over the proposed philosophical implications above. Are they too strong? Warranted? Do you have sceptical doubts about using this research to alter your view of these research questions?